Many people remain missing in Canada's Quebec province, a day after a train carrying crude oil hurtled off track and exploded in the center of a town, destroying dozens of buildings and killing at least one person.

The accident in the lakeside town of Lac-Megantic occurred in the wee hours of Saturday morning, when the town center was crowded with weekend partygoers.

Officials have confirmed one fatality, but say they expect the toll to rise. Media reports indicate up to 80 people could be missing.

The derailment caused four of the train's more than 70 cars to explode in the middle of the town, sending a gigantic fireball into the night sky. The fires destroyed dozens of buildings, including stores and at least one bar, and continued burning for hours as both Canadian and U.S. firefighters fought the blazes.

The accident forced up to 2,000 people to evacuate from their homes - a third of Lac-Megantic's 6,000 residents.

The cause of the derailment is still not known. The rail company that operated the train - the Montreal, Maine & Atlantic Railway - said the train's conductor parked it shortly before midnight Friday. The rail line says it believes the conductor set the brakes properly, but that "sometime after, the train got loose," speeding into the town "under its own inertia," before derailing.

Canada's transportation safety agency is investigating.

Montreal, Maine & Atlantic owns more than 800 kilometers of track in Canada's Quebec and New Brunswick provinces and the northeastern U.S. states of Maine and Vermont.

Canadian Prime Minister Stephen Harper called the accident "shocking and truly devastating." He said his "thoughts and prayers" are with the people of Lac-Megantic and that the government is ready to provide assistance.

Just last week, Canada suffered another derailment of a train carrying petroleum products. The train went off track in Calgary, Alberta, when a flood-damaged bridge sagged toward the still-swollen Bow River. The derailed rail cars were able to be removed without spilling their cargo.